This invention relates generally to antenna systems and, more particularly, relates to broadband antennas.
Broadband antennas used in wireless telecommunication systems are designed to receive or transmit linear polarized electromagnetic signals. The sense or direction of linear polarization is measured from a fixed axis and can range from horizontal polarization (90 degrees) to vertical polarization (0 degrees). Many broadband antennas are designed to employ dipole elements to receive or transmit the signals. These elements are mounted above an artificial ground plane, which is typically an electrically conducting plate, and the elements are connected together via feed lines. These feed lines are often in the form of coaxial cable.
One subset of broadband antennas consists of two dipoles and two feed lines that form a polarized antenna. The polarized antenna can be a dual polarized antenna, consisting of a horizontally polarized portion and a vertically polarized portion. It can also be a xc2x145 degrees polarized antenna with the proper orientation.
The dipole elements are typically made from multiple pieces and soldered or welded together. As the number of dipole elements is increased, the manufacture of the antenna increases in complexity, time-consumption, and expense. For high frequency operation, the expense increases further due to the tolerances required for operation in the desired frequency range. What is needed is a way to economically produce the elements and the antenna assembly.
In view of the foregoing, a multiple dipole element is manufactured from a single sheet of a low loss conducting material. The multiple dipole element may be stamped, punched, cut, or etched and then bent into the proper shape or alternatively die-cast. The multiple dipole element is attached to a reflector plate via a base and feed lines are located along the top and bottom surfaces of the element. The combination of the multiple dipole element and feed lines forms a multiple dipole set of radiation elements.
Several dipoles can be added to the multiple dipole element to achieve different radiation patterns. The dipole elements can also be formed into different shapes to achieve different lobe shapes.
In one embodiment, a tab is located at the center of each feed of the multiple dipole element and is bent at either an upward angle or a downward angle. The tab can be bent at any angle and the tabs attenuate the radiation caused by the slot.
Additional features and advantages of the invention will become more apparent from the following detailed description of illustrative embodiments when taken in conjunction with the accompanying drawings.